Medical devices that can be delivered by oral administration may be advantageous over other types of integration methods such as implantation. Orally ingestible devices may offer high degrees of patient compliance, exhibit minimal risk of infection, and obviate many complications associated with chronically implanted devices.
Typically, orally ingestible devices perform some type of biosensing function, which could be critical to gathering important vital information about a patient. For example, cameras may be used to image tissue within the gastrointestinal (GI) tract of the patient in order to identify potentially cancerous regions. Biosensors may be used to measure core temperature, potential hydrogen (pH), or dissolved oxygen concentration, which may provide real time insight into digestive function. Subsequent interrogation of the sensors is typically performed through wireless communication. These devices may include microelectronic components that are typically powered using high performance on-board battery systems that are fabricated from potentially toxic materials. The batteries are hermetically sealed in robust corrosion-resistant packaging materials that reduce the likelihood of leakage.
Innovations in battery materials aim to continuously improve a variety of figures of merit related to battery performance. These innovations include novel material compositions for the anode, cathode, separator, electrolytes, functional electrolyte species, and external packaging of the battery. The material compositions are generally designed to improve operating characteristics of the battery such as energy, density, and power. Many of these innovations in materials and device design are driven by economic considerations with specific applications in mind. For example, some battery innovations would be better suited for large scale energy storage in power plants while others might be better suited for mobile applications such as energy storage in vehicles or personal electronic devices. The primary factors for large energy storage device design tend to be defined by economic considerations.
Cost constraints may be less prohibitive for the design of batteries for medical devices. Batteries designed for chronic implants may include high performance materials that may be potentially highly toxic. Potential toxicity risks may be mitigated by utilizing robust packaging to hermetically seal the battery. This prevents the potential escape of toxic materials into the surrounding tissue. The general design guidelines that are commonly applied to high performance batteries aim to achieve long operation lifetimes (often over 10 years) and facile options for battery maintenance including minimally invasive battery replacement or wireless power transmission for recharging. Batteries that adopt this paradigm are often relatively large, bulky devices that may be suitable for chronic implants such as pacemakers, but may not be suitable for oral ingestion.